Silane terminated sulphydric acid based michael polyaddition polymers

ABSTRACT

Terminated silane polymers obtained by addition reactions between an organic silicon derivative and the terminal functional groups of linear or branched polymers obtained by Michael polyaddition reactions of sulphydric acid (H 2 S) with organic compounds which have at least two alkylenic double bonds activated by the presence, in the alpha position with respect to each alkylenic bond, of an electronegative group.

FIELD OF THE INVENTION

The present invention relates to a new type of polymer which is producedby the addition reaction of an appropriate organic derivative of siliconwith the terminal functional groups of linear or branched polymers,obtained by the Michael polyaddition reaction between an inorganiccompound such as sulphydric acid (H₂S) and organic compounds whichcontain at least two alkylenic double bonds activated by the presence,in the alpha position with respect to each alkylenic double bond, of anelectronegative group. Said silane terminated polymer, organic-inorganichybrid, generated by the alternation of organic and inorganic monomericcomponents, in conditions of the absence of humidity is stable and has anature of viscous fluid or fusible solid as a function of the organicmonomers and the preselected molecular weight, but simply upon exposureto humid air or upon contact with humidity containing materials, reactsby polymerising by means of a hydrolysis mechanism and successiveauto-condensation of the terminal silane groups, converting into a crosslinked solid state which can be hard and strong like a resin or elasticand flexible like a rubber. Such polymer constitutes the basis foradhesive compounds and monocomponent hydrosetting sealants and reactivehot-melt resins.

PRIOR ART

The adhesives and sealants sector represents an area in continuous andrapid development due to the progress in materials science and to theresulting request for substances capable of joining two parts, havingdifferent or the same nature, without the assistance of mechanicaldevices. Since, in addition, in recent years the request for noncontaminating products has grown, research has for some time beenoriented towards the attainment of materials having good mechanicalproperties, adhesive capacities on different substrates (naturalorganics, plastics, inorganics, metals) and respect for the workingenvironment. All the volatile organic substances are however still lesstolerated, such as for example the solvents or the unreacted monomers,able to release themselves upon application of the product.

Over the last decades, in the monocomponent hydrosetting sealantssector, polyurethane polymers have dominated in virtue of theirsimplicity of synthesis, of modest costs and their optimalphysico-mechanical properties. Today, however, the problem regarding theenvironment is particularly felt for this type of product, due to thesignificant concentrations of free monomer which can be present (forexample, toluene-di-isocyanate or methylene diphenyl-di-isocyanate).

The monocomponent hydrosetting polymers of the silicone family do nothave this problem, but they do not possess any of the particularcharacteristics of the polyurethanic based systems such as, for example,paintability; they therefore have limited applications in some sectors.

The polysulphuric based materials, other than having an unfavourablebicomponent nature for which they must be mixed with another product atthe time of application, are increasingly more difficult to find on themarket due to the environmental problems bound to their production and,hence, are increasingly less used.

With the polyurethanic based systems, the problem of noxious freemonomers from the chemical point of view has been mainly dealt with thetransformation of the isocyanate groups, by exploiting the reactivitytowards an appropriate organic function (containing reactive hydrogens)belonging to from alkoxy- or acetoxy-silane species; such species arecapable, upon exposure to humidity, of hydrolysing to form silanolicgroups and, successively, of auto-condensing to form siloxanic bridges,thus generating, the cross linking of the product and maintaining thehydrosetting monocomponent nature (as examples we cite: Emmerling etal., U.S. Pat. No. 4,857,623; Brode et al. U.S. Pat. No. 3,632,557;Blanco, U.S. Pat. No. 4,426,506). The isocyanate terminated polymers,and therefore also the monomer residues, are transformed into silaneterminated systems. The main inconvenience is bound to thetransformation of the isocyanic groups into urethane or ureic orthiocarbamic groups with an increase in the number of hydrogen bonds andviscosity. This necessitates the unwelcome presence of solvents in thefinal product.

Therefore, one can say that the construction technique for silaneterminated macromolecules, capable of hydrolysing and auto-condensing,represents a useful method for producing hydrosetting polymers usable inthe adhesives and sealants sector.

Silane terminated polyethers are, in addition, known in the art (Isayamaet al. U.S. Pat. No. 3,971,751; Takase et al. U.S. Pat. No. 4,444,974).

Also known in the art are silane terminated polymers obtained by theaddition reaction of an organofunctional silicon compound havinghydrolysable groups on the terminal functional groups of the Michaelpolyaddition polymers (Galbiati et al. U.S. Pat. No. 6,221,994 in thename of the applicant). More precisely, are described silane terminatedpolymers obtained by the Michael polyaddition reaction of organiccompounds which contain at least two reactive hydrogens on organiccompounds which contain at least two ethylenic double bonds activated bythe presence, in the alpha positions of each ethylenic bond, of anelectronegative group. Still more in particular, are described polymershaving repeated structural units containing the β-thioether-ester bondsobtained by the reaction of dithiols with dimethacrylates. Said silaneterminated polymers are the basis for hydrosetting monocomponentadhesive and sealant products.

The Michael polyaddition polymers obtained by the reaction ofbifunctional nudeophilic organic molecules, such as for example thediols, the diamines and the dithiols, with organic molecules havingdouble bonds activated by electronegative groups in the alpha positionsin alkylenic bonds, such as for example the diacrylic derivatives, thedimethacrylics, the dinitro olefins, the divinyl sulphones and thedivinyl sulphoxides are well known in the art (Bayer, O. Angew. Chem.61, 229, 1949; Hulse, U.S. Pat. No. 2,759,913; Nuyken et al. Makromol.Chem. 191, 2465, 1990). The molecular weight of said linear polymers isa function of the ratio between the bifunctional monomer reagents andthen, therefore, can be preselected as a function of the ratio itself,whilst the terminal functional groups are preselected from amongst thoseof one of the two monomeric species and, more precisely, are those ofthe species in excess. Since the reaction has the characteristics of astep reaction at the total conversion of the product in defect the MeanNumerical Degree of Polymerisation, <P_(n)>, is given by:<P_(n)>=(1+r)/(1−r), where r represents the ratio between the amount ofmonomer in defect and that in excess and, hence, the molecular weightdepends only on r. When r=1, theoretically, one obtains the cyclic chainwith the absence of functional groups useful for the successivesilanisation, whilst when r≠1 the molecular weight is directly derivedfrom the ratio r selected and the polymers obtained have the monomerterminal groups in excess.

In the case in which monomers having functionality greater then two areused to produce a polyfunctional step polymerisation, for example of thetype:

it is possible to produce polymers with different branching coefficient,α, as a function of the functionality; f, of the branching species andthe initial of proportions between the different species, and that is asa function of the ratio r′ between the number of functional groups A andB initially present and of ρ, which represents the fraction of A groupsbelonging to the branching unit (A_(branching unit)/A_(total)). In facton total conversion of the BB in defect monomer one has:α=ρ/(r′−1+ρ)whilst the mean numerical polymerisation degree is given by:<P _(n) >=[f(1−ρ−+1/r′)+2ρ]/[f(1−ρ+1/r′−2p _(a))+2ρ]where p_(a) is the fraction of the A groups which have reacted.

For polymers useful for successive silanisation it is desirable that ado not over exceed the critical value a_(c), that is the Gelling Point,beyond which one has a rapid transformation of the reaction mixture fromviscous liquid to elastic material with infinite viscosity, insoluble inall non degrading solvents.

Therefore Michael polyaddition represents, a good method for thesynthesis of telechelic polymers, having pre-established terminalfunctional groups and molecular weight, and, in the case of the use ofmonomers having more than two useful functional groups per molecule,having pre-established degree of branching; in addition, as a functionof the supply of the monomers to the reactor, it is possible to controlthe distribution of molecular weights. As a consequence, it represents agood method to prepare polymers useful for successive silanisation, thesubject of this patent.

Polymers having a thioether nature are useful in as much as theintroduction of sulphur groups into the chain imparts particularphysico-chemical characteristics, such as for example greater stabilityto solvents and to petrols. Polymers having β-thioether-ester nature areparticularly useful since, in addition to that expressed above, theester bonds represent a simple way for the synthesis of species havingactivated double bonds and, more precisely, of α,β-unsaturatedcarbonylic species. As a consequence this combination is particularlyadvantageous, both with regard to the final properties of the product,and in terms of the production of the material itself.

However, the silane terminated polymers cited in the U.S. Pat. No.6,221,994, prepared from dithiols and organic compounds which contain atleast two activated double bonds, suffer from the serious problem boundto olfactory perception, possessing unpleasant odours (typical of rotteneggs) which make successive working problematic and which, persist intothe final product, not favouring their commercialisation.

The olfactory problem can be explained by considering the organic natureof the dithiols, of the impurities contained in them, of the by-productswhich can be generated in reaction environment, as well as consideringthe peculiarity of the SH group.

Thiols possess an extremely offensive odour for which the human nose hasa very low detection threshold, in the order of parts per billion (ppb);for example the atmospheric detection thresholds of methyl-mercaptan andethyl-mercaptan are around 1 ppb. In addition they are easily oxidisedto disulphurs by mild oxidising agents or by atmospheric oxygen in thepresence of for example amines as catalysts, according to the followingscheme:

The alkyl sulphides (R—S—R), disulphides (R—S—S—R) and poly sulphides(R—S_(n)—R) are odorous liquids, more or less like the thiols. Theatmospheric detection threshold of dimethyl-sulphide is equal to 1 ppb,that of diethyl-sulphide of 0.25 ppb, whilst dimethyl-disulphide is onlyslightly less odorous of the corresponding methyl-mercaptan, and thepoly sulphide Me-(S)₂₋₄-Me has a threshold equal to that ofmethyl-mercaptan.

The industrial synthetic pathways of the thiols exploit thetransformation of the corresponding alcohols or terminal alkenes withsulphydric acid, according to the scheme:

An additional synthetic pathway, even if of minor industrial importance,envisages the transformation of the corresponding halogen derivativesthrough reaction with the monosodium salts of sulphydric acid (NaSH),according to a nucleophilic substitution scheme:

In all these syntheses, as it can be observed from an analysis of thepatent literature, the main problem is the formation of thecorresponding dialkyl-sulphides, since the RSH species formed cancondense with the hydroxyl groups or addition further with the nonreacted double bonds, or can undergo further nucleophilic substitutionson the halogen. Other by-products, obtained through oxidation, are thedialkyl-disulphides, also these possessing extremely unpleasant odours.

In addition to these considerations it should be born in mind that theS—H bond is capable of significant formation of hydrogen bonds.

These considerations lead to the following conclusions, capable ofexplaining the presence of residual odours:

-   a) even preparing the Michael polyaddition polymers lacking in    dithiols with respect to the species having two activated double    bonds and reaching the maximum conversion of the SH groups ([SH]˜0    according to traditional analytical methods), one obtains small    quantities of unreacted dithiols which, even being negligible from    the point of view of the properties of the polymer, are able to    generate an unpleasant odour; such amounts are eliminated with    difficulty, even at low pressures, due to the presence of hydrogen    bonds between the SH group, the oxygen of the carbonylic group and    the sulphur of the β-thioether-ester structure, the problem is    aggravated by the viscous nature of the polymer. The odour generated    by the monomer residue remains unaltered during the successive    silanisation step since the reaction involves the use of an    organo-silane species having a nucleophilic functional group with    active hydrogens and, therefore, inactive towards the mercaptan    species;-   b) the odour emitting organo-sulphuric and cyclic disulphuric    impurities which can be contained within the dithiols and which are    bound to the methods of preparation are chemically inactive to the    reactions involved in the synthesis cycle of the polymers forming    the subject of the patent;-   c) as reported in the examples in U.S. Pat. No. 6,221,994, the    favoured environment for the Michael polyaddition reaction between    dithiols and organic species having two activated double bonds, and    more precisely between dithiols and diacrylic and dimethacrylic    species to generate the β-thiother-ester structure, contemplates the    presence of tertiary amines such as, for example, triethyl-amine    able to generate the nucleophilic mercaptide ions species, the    active species in the Michael addition. Therefore the environment    favours giving rise to secondary reactions, such the formation by    oxidative routes of organic disulphides, chemically inactive in the    successive silanisation step;-   d) it is also considered that possible dithiol impurities,    monofunctional in nature, are difficult to trace and to separate,    and are able to act as such chain terminating agents resulting in a    block in the growth of the chain and a reduction of the molecular    weights with respect to the values pre-established on the basis of    the ratio between the amounts of the monomers.

The need to obtain silane terminated Michael polyaddition polymers withβ-thioether structures, avoiding the above listed inconveniences throughthe use of dithiols was therefore felt.

SUMMARY OF THE INVENTION

The applicant has surprisingly and unexpectedly found that, a new silaneterminated polymer obtained by the addition reaction between an organicderivative of silicon and the terminal functional groups of Michaelpolyaddition polymers obtained by the reaction of organic compoundswhich contain at least two alkylenic double bonds activated by thepresence, in the alpha positions of each alkylenic bond, of anelectronegative group with an inorganic compound such as sulphydric acidand able to convert from, a viscous fluid or fusible solid state into across-linked and insoluble solid state which can be hard and resistantlike a resin or soft and flexible like a rubber, does not present theinconveniences of the unpleasant smells of the silane terminatedpolymers obtained by Michael polyaddition with mercaptans.

DETAILED DESCRIPTION OF THE INVENTION

The subject of the present invention is therefore constituted by asilane terminated polymer obtained by the addition reaction between anorganic silicon derivative and the terminal functional groups of linearor branched polymers obtained by the Michael polyaddition reaction ofsulphydric acid (H₂S) with organic compounds which have at least twodouble alkylenic bonds activated by the presence, in the alpha positionwith, respect to each alkylenic bond, of an electronegative group.

In a preferred embodiment of the present invention the organic siliconderivative has the following general formula:

with a=0, 1, 2; b=0, 1 and wherein:

-   X=selected from the group consisting of halogen, alkoxy, acyloxy,    ketoxime, amine, amide and mercaptan radicals;-   R¹=monovalent hydrocarbon group;-   R²=bivalent substituent selected from the group consisting of    hydrocarbon, ether-hydrocarbon, amino-hydrocarbon radicals;-   Z=substituent selected from the group consisting of:    wherein R″ represents a monovalent hydrocarbon group.

The structures of the linear Michael polyaddition polymers useful forbeing silanated according to the present invention, prepared frommonomers having two activated double bonds and H₂S, and characterised bydifferent terminal functional groups as a function of the ratio betweenthe monomers, can be represented as in scheme (2) and scheme (3).

wherein:

is any organic compound having two activated double bonds and n is aninteger greater than or equal to 1.

Further examples of structures of the branched Michael polyadditionpolymers useful for being silanated according to the present invention,prepared from at least one monomer having more than two activated doublebonds and H₂S, and characterised by different terminal functional groupsas a function of the ratio between the monomers, can be represented inan exemplified manner. (which does not wish to and cannot correspond toreality) as in scheme (4) and scheme (5).

wherein:

is any organic compound having two activated double bonds and n is aninteger greater than or equal to 1.

is any organic compound having three activated double bonds and n is aninteger greater then or equal to 1.

Not reported herein, for the obvious difficulties bound to the graphicalrepresentation, are all the branched structures obtainable withmonomers-having activated double bonds in numbers greater than two andwith the combinations of monomers With functionalities greater than twowith monomers with functionalities equal to or greater than two. It isevident, however, that for the purpose of this patent any combination ofmonomers with different degree of functionality able to produce aviscous fluid polymer is useful (at any temperature and below,accordingly, to its gelling point) having terminal functional groupsuseful for the successive silanisation with organic derivatives ofsilicon, preferably with the silanes of formula (1).

The mean numerical molecular weights of such polymers are pre-selectedas a function of the ratio between the monomers and are selected as afunction of the nature of the monomers themselves and of the final useto which the polymer is destined. Such values can be comprised ofbetween 200 Daltons and 60000 Daltons.

In particular, the silane terminated polymers which one obtains byreacting the polyaddition polymers as described above with an organiccompound of silicon, according to the present invention, in which theorganic compound of silicon has the general formula (1), and that are afurther subject of the present invention, are characterised by thefollowing terminal structures, which for reasons of simplicity arerepresented, herein only by the linear polymers:

with Z=H;and wherein R, R², R¹ and X have the same meaning as indicated in thegeneral formulas (1), (2) and (3); a=0,1,2; b=0,1;

with Z=SH, NH₂, NHR″ and Y=S, NH, NR″;and wherein R, R″, R², R¹ and X have the same meaning as indicated inthe general formulas (1), (2) and (3); a=0,1,2; b 0,1;

and wherein R, R², R¹ and X have the same meaning as indicated in thegeneral formulas (1), (2) and (3); a=0,1,2; b 0,1.

Preferably, the organic compounds of silicon of formula (1) are selectedfrom the 6 group consisting of:

(Isocyanate alkyl)alkoxysilanes:O═C═N—R³—Si(R⁴)_(a)(OR⁵)_(3-a)  (1a)(Amino'alkyl)alkoxysilaness:H₂N—R³—Si(R⁴)_(a)(OR⁵)_(3-a)  (1b)(Glycidoxyalkyl)alkoxysilanes:O[CH₂—CH)—CH₂—O—R³—Si(R⁴)_(a)(OR⁵)_(3-a)  (1c)(Mercaptoalkyl)alkoxysilanes:H₂—R³—Si(R⁴)_(a)(OR⁵)_(3-a)  (1d)([meth]acrylate alkyl)alkoxysilanes:CH₂═C(R⁶)—COO—R³—Si(R⁴)_(a)(OR⁵)_(3-a),  (1 e).wherein:

-   R³=divalent alkyl radical containing from 1 to 8 carbon atoms;-   R⁴ and R⁵=alkyl radicals containing from 1 to 4 carbon atoms;-   R⁶=H or CH₃;-   a=0,1,2.

In a particularly preferred embodiment of the present invention theorganic compounds of silicon of formula (1) are selected from the groupconsisting of:

-   (3-mercaptopropyl)trimethoxysilane;-   (3-mercaptopropyl)methyldimethoxysilane:-   (3-[meth]acryloxypropyl)trimethoxysilane;-   (N-nButyl,3-aminopropyl)trimethoxysilane;-   (N-Ethyl,3-aminoisobutyl)methyldiethoxysilane;-   (3-glycidoxypropyl)trimethoxysilane.

In a preferred embodiment of the present invention, the organiccompounds useful for Michael polyaddition, having at least two activateddouble bonds, are selected from the group consisting of:W′[—C(R⁷)═CH₂]₂  (9)Q[-W—C(R⁷)═CH₂]₂  (9a)Q[-W—C(R⁷)═CH₂]₃  (9b)Q[-W—C(R⁷)═CH₂]₄  (9c)wherein:

-   W=electron-attractor group selected from the groups consisting of:-   —SO—, —SO₂—, —O—, —CO—;-   W=electron-attractor group selected from the group consisting of:-   —SO—; —SO₂—, —O—, —CO—, —O—CO—;-   R⁷=—H or —CH₃;-   Q=divalent, trivalent or tetravalent group selected from the group    consisting of hydrocarbon radicals, hetero-hydrocarbons, polyethers,    polyesters, which can contain a repeating unit and hence have    variable molecular weight; In a particularly preferred embodiment    the acrylic and/or methacrylic organic compounds have the general    formulas:    wherein m=2, 3, 4; R⁷═H or CH₃; R⁸ is selected from the group    consisting of: di-, tri- or tetra-valent polyethers which consist    essentially of a —OR⁹— chemically combined unit, wherein R⁹ is a    divalent alkyl group having from 2 to 4 carbon atoms; di-, tri- or    tetra-valent linear or branched aliphatic alkyl radicals, preferably    from 1 to 50 carbon atoms; di-, tri- or tetra-valent aromatic    radicals, preferably from 6 to 200 carbon atoms; di-, tri- or    tetra-valent linear or branched aryl radicals, preferably from 6 to    200 carbon atoms or R⁸ is one or more combinations of said    polyethers, alkyl radicals, aromatic radicals and aryl radicals.

Amongst the organic compounds having at least two activated alkylenicbonds one can mention for the purposes of example the followingstructures:

-   H₂C═C(R⁷)—SO₂—C(R⁷)═CH₂,-   H₂C═C(R⁷)—SO—C(R⁷)═CH₂,-   H₂C═C(R⁷)—O—C(R⁷)═CH₂,-   CH₃CH₂C[CH₂O—CO—C(R⁷)═CH₂]₃,-   C[CH₂O—CO—C(R⁷)═CH₂]₄,-   O{CH₂C(C₂H₅)(CH₂O—CO—C(R⁷)═CH₂)₂}₂,-   H₂C═C(R⁷)—CO—CH₂CH₂O—CO—C(R⁷)═CH₂,-   H₂C═C(R⁷)—CO—CH₂CH(CH₃)CH₂O—CO—C(R⁷)═CH₂,-   C[CH₂[OCH₂CH(CH₃)]_(n)—CO—C(R⁷)═CH₂]₄,-   H₂C═C(R⁷)—CO—O(CH₂CH₂O)_(n)—CO—C(R⁷)═CH₂,-   CH{CH₂O[CH₂CH(CH₃)O]_(n)—CO—C(R⁷)═CH₂}₃,-   H₂C═CH—SO₂—(CH₂CH₂O)_(n)—CH₂CH₂SO₂—CH═CH₂,-   H₂C═C(R⁷)—CO—O[R—O—CO—R′—CO—O]_(n)—R—O—CO—C(R⁷)═CH₂,    wherein: R⁷═H or CH₃; R and R′=alkyl or aryl radicals.

Preferably, the organic compounds useful for Michael poly addition,having at least two activated double bonds, are selected from the groupconsisting of: di, tri., tetra-acrylates; di, tri and tetramethacrylates; di-, tri and tetra-vinyisulphones. Amongst thedi-acrylate and di-methacryliate organic compounds the most preferredaccording to the present invention are selected from the groupconsisting of:

-   compounds of general formula (11)    wherein:-   R⁷═H or CH₃; R¹⁰=selected from the group consisting of —CH₂CH(CH₃)—,    —CH₂CH₂, —CH₂CH₂CH₂CH; —CH₂CH(CH₃)—CH₂—; n′=an integer comprised of    between 1 and 400, preferably between 1 and 200, still more    preferably between 1 and 50;-   compounds of formula (12):    wherein n=is an integer comprised of between 0 and 10 and R⁷ is H or    CH₃.

Absolutely preferred between the compounds of formula (11) are thecompounds in which R⁷ is hydrogen and R¹⁰ is —CH₂CH(CH₃)—, i.e. thepolyisopropylenglycolidiacrylates.

Amongst the tri-acrylate and tri-methacrylate organic compounds thepreferred are:

wherein:

-   R⁷═H or CH₃; n″=an integer comprised of between 0 and 400,    preferably between 0 and 200, still more preferably between 0 and    50.

Amongst the vinyl-sulphonic the preferred are:

wherein: R¹¹ is selected from the group consisting of —CH₂—CH(CH₃),—CH₂—CH₂—, —CH₂CH₂—CH₂CH₂—; —CH₂CH(CH₃)—CH₂—; n′″ an integer comprisedof between 0 and 400, preferably between 0 and 0.200, still morepreferably between 0 and 50.

The structures of the linear Michael polyaddition polymers useful forbeing silanated, prepared from diacrylates or dimethacrylates, or fromdivinylsulphones, and H₂S, and characterised by different terminalfunctional groups as a function of the ratio between the monomers, canbe represented as in the scheme (17), scheme (18), schemes (19) and(20).

wherein: R⁷, R¹⁰, R²², n, n′ and n′″ maintain the same meaning asindicated above and p=0.1.

Not reported herein for obvious reasons bound to the difficulties ofgraphical representation, are all the branched structures obtainablewith monomers having activated double bonds in numbers greater than twoand with the combinations of monomers with functionality greater thantwo with monomers with functionality equal to or greater than two. It isevident, however, that in agreement with the present invention and withthe final properties of the material, any combination of monomers ofdifferent nature and different degree of functionality able to produce aviscous fluid polymer (at any temperature; below, then, its gellingpoint having terminal functional groups useful for successivesilanisation is useful, preferably with silanes of the structure (1).

The silane terminated polymers, subject of the present invention can berepresented, as a means of example which should not be seen asexhaustive with respect to all the exposed combinations and subject ofthe present invention, as in scheme (21) and scheme (22), by reactingthe polyaddition polymers (17) and (18) with the silanes (1d) and (1e).

wherein:

and R³, R⁴, R⁵, R⁶, R⁷, R¹⁰, a, n and n′ maintain the same meaning asindicated above.

The present invention consists in the use of a monomer having aninorganic nature, such as sulphydric acid (H₂S), in place of the organiccompounds having two active hydrogens described in the U.S. Pat. No.6,221,994, preferably with particular classes of organic compounds whichhave at least two activated alkylenic double bonds, in the process ofsynthesising a silane terminated polymer obtained by Michaelpolyaddition reaction.

Such monomer is a diprotic inorganic acid and, under basic catalyticconditions such as these generated, for example, by tertiary amines, isable to behave as a bifunctional species in the Michael polyaddition.

With the present invention the structure of the repeating structuralunit is therefore modified from β-thioethers-[activating group](example, β-thioethers-esters) as are possible from all the possiblecombinations of the structures reported by U.S. Pat. No. 6,221,994,becoming β-thioethers-[activating group]₂ (e.g., β-thioethers-diesters)since only a single sulphur atom is present in the beta position of thetwo activating groups, and the organic portion present between two Satoms is eliminated; that is clarified by the following structures:

-   -X′-C—C^(β)—S—R—S—C^(β)—C—-X- (U.S. Pat. No. 6,221,994)-   -X′—C—c^(β)—S—C^(β)—C-X′- (present invention)    wherein X′=activating group, R=organic portion, C^(β)=carbon in    position β with respect to the activating group.

Sulphydric acid, having a somewhat low atmospheric perceptibilitythreshold (10-20 ppb), overcomes the problems related to the odours ofthe final polymer thanks to the following properties:

-   a) in the case of the presence of residual quantities of unreacted    monomer, it is easily removed at low pressure from the viscous mass    thanks to its gaseous inorganic nature at environment temperature    and pressure (T_(eb)=−60,3° C.);-   b) the impurities which can be present in the sulphydric acid are    not sulphuric or disulphuric organic type having extremely    unpleasant odours (such as however in the case of the dithiols),    since the industrial synthesis envisages the reaction starting from    heating hydrogen and sulphur, according to the scheme:    A typical composition of H₂S at 99.5% vol can include the presence    of maximal concentrations of the following substances: H₂O=0.001%,    CO₂=0.01%, COS=0.2%, CS₂=0.2%, CH₄=0.05%, N₂=0.05%; in addition it    can contain traces of H₂;-   b) possible oxidation products (e.g. SO₂, SO₃) which can be    generated during the Michael polyaddition have inorganic gaseous    nature and do not possess repugnant odours such as the organic    oxidation products obtained from the thiols (sulphurs, disulphurs);    in addition they are spontaneously liberated from the reaction mass    or are however easily removable at low pressure;-   c) the diprotic nature of the gaseous H₂S species is able to ensure    the dual-functionality of the monomer in the Michael polyaddition,    guaranteeing high correspondence between the molecular weight    predetermined by the ratio between the monomers and the molecular    weight obtained experimentally. That is not obvious in the case of    the thiols for which monofunctional species can be present,    particularly on products for industrial use which can have purity of    less than 98% in weight.

A further object of the present invention is constituted by thesynthesis process for a silane terminated polymer obtained by theaddition reaction between an organic derivative of silicon and theterminal functional groups of linear or branched polymers obtained bythe Michael polyaddition reaction of sulphydric acid (H₂S) with organiccompounds which have at least two alkylenic double bonds activated bythe presence, in the alpha position with respect to each alkylenic bond,of an electronegative group, the process in which the Michael additionreactions are catalysed by organic bases, preferably tertiary amines,more preferably tertiary amines selected from the group consisting oftriethylamine, 1,8-diazadicycl6[5.4.0.]undecene-7 (DBU),1′,4-diazadicyclo[2.2.2]octane (DABCO). Regarding this invention all thepolymers, obtained with a ratio between the quantities of the monomershaving activated double bonds (pure or mixed with species with differentnature and different functionality) and the H₂S monomer such as toguarantee the presence of the free functional groups necessary for thesuccessive silanisation, are useful, making dependent the selection ofthe nature and the number of the functionalities and the ratio of H₂S onthe final use to which the polymer itself is addressed, on preselectedterminal functional group type and molecular weight, as well as, on thepreselected degree of branching.

According to the present invention the silanated polymers, obtained bythe Michael polyaddition of an inorganic compound such as sulphydricacid and organic compounds having at least two activated alkylenicdouble bonds, by simple exposure to atmospheric humidity, and withoutthe further additions of other reactive substances, completelycross-link passing from the fluid state (at a certain temperature) tothat of an insoluble solid.

With that aim the Michael polyaddition polymers between H₂S and organiccompounds according to the present invention, are made to react withorganic derivatives of silicon, preferably the silicon organic compoundsof formula (1), which carry both a reactive functional group suitable toreact with the terminal functional group of the polyaddition polymer,and appropriate, easily hydrolysable and condensable groups. The silaneterminated polymers thus obtained are stable and maintain their viscousfluid or fusible solid state in anhydrous conditions, whilst, if exposedto atmospheric humidity, they transform into solid materials insolublein any non degrading solvent following cross linking generated by thehydrolysis and successive auto-condensation of the silanolic groups onthe terminal silicon atoms. Such cross linking mechanism is known andamply described in the art.

More particularly, according to the present invention, the Michaelpolyaddition polymers are all these functionalised at the extremities,linear or branched, obtainable by the Michael polyaddition reactionbetween sulphydric acid and organic compounds having at least twoactivated alkylenic double bonds, making dependent the selection of thenature of the monomers, of their functionality and of their molecularweight (in the case of the presence of repeating units) on the finalproperties of the polymer; in addition making the selection of the ratiobetween the quantities of sulphydric acid (H₂S) and of the organicmonomers dependent on the preselected type of terminal functional groupand molecular weight of the polymer, as well as making the selection ofthe nature of the silane compound dependent on the type of terminalfunctional group of the polyaddition polymer and the functionality ofsaid silane compound on the degree of cross linking in the finalmaterials, once the passage from viscous fluid or fusible solid toinsoluble cross linked solid is undergone by exposure to humidity.

In solvent free systems the mean molecular weight of the Michaelpolyaddition polymer is comprised between the minimum obtainable as afunction of the preselected organic monomers and a maximum of around70000. Higher molecular weights could determine viscosity too high forpractical use. In the presence of solvents the molecular weight of.70000 can be exceeded, if the terminal functional groups are present innumbers such as to obtain, following reaction with the, appropriatesilane functional groups, a sufficiently high percentage of, terminalsilane groups and therefore a structure with a useful degree of crosslinking following vulcanisation by exposure to humidity.

Since the speed of the hydrolysis reaction of the alkoxysilane groupsand the condensation of the silanols which results in the cross linkingof the silane terminated. Michael polyaddition polymers is moderate, itis generally preferable, even if not strictly necessary, to use acatalyst. Any catalyst of hydrolysis and condensation of the silanolscan be used. Examples of such compounds are the metallic salts ofcarboxylic acids such as dibutyl tin dilaurate, tin octoate and thelike, organic titanium derivatives such as the alkyl titanates and thelike, and every other acid or basic catalyst. The amount of catalyst ispreferably comprised of between 0.1 and 10 partsin weight per 100 partsin weight of polymer.

The silane terminated polymers according to the present invention can betreated with loads normally used in the field, of polymers; for examplereinforcing loads such as: pyrogenic silica, precipitated silica orcarbon black; or non reinforcing loads such as: precipitated or groundcalcium carbonate, magnesium carbonate, kaolin, talc, titanium oxide,iron oxides, zinc oxides or mixtures thereof, fibrous organic orinorganic materials. Furthermore, all the loads well known in the rubberindustry sector can be used in addition to these cited above, singularlyor in mixtures, each conferring their individual characteristics ontothe polymer. The choice between the different loads must be carried outtaking into account the mechanical properties (elongation to rupture,breakage load, hardness, resistance, elasticity, etc.) required of thefinal product, not forgetting the rheological characteristics of theproduct prior to vulcanisation (viscosity, density, flow, thixotropy,etc.).

Together with the mineral loads, the silane terminated polymersaccording to the present invention can also be modified withplasticisers, generally used to modify the mechanical and Theologicalproperties of the final product. The fundamental requirement of theplasticiser used is its compatibility with the polymer. Only partiallycompatible plasticisers are expelled over a variable period of timedepending on the degree of compatibility, giving rise to unmixingphenomena prior to vulcanisation and exudation following vulcanisation.Every plasticiser known in the art is compatible with the silaneterminated Michael polyaddition polymers according to the presentinvention. Amongst the plasticisers in particular are considered thephthalic acid esters, the adipic acid esters, the phosphoric esters, theepoxidated soya oils, the chlorinated paraffins.

In addition to the loads and the plasticisers such as these above, otheradditives can be used in mixtures with the polymers of this invention:pigments, antioxidants, UV stabilisers, thixotropic additives, additivesto improve adhesion, in particular the phenolic resins and the epoxidicresins.

Since the silane terminated polymers are particularly sensitive tohumidity, the loads, the plasticisers, the other additives such as theseabove and in general all the products which are added must be dehydratedprior to use.

Some examples are reported below for non limiting illustration of thepresent invention.

EXAMPLE 1

In a pressure reactor, 57.2 g (28.30 mmol) of a polyoxypropyleneglycoldiacrylate having a mean numerical molecular weight <M_(n)> equal to2021 g/mole are mixed with 0.857 g (25.15 mmol) of sulphydric acid(34.08 g/mole) in the presence of diaza bicyclo undecene DBU (0.1% byweight). It is left to react with agitation at a temperature of 70° C.until the complete conversion of the mercaptan groups.

The linear Michael polyaddition polymer (A) thus obtained has terminaldouble bonds (¹H-NMR analysis), viscosity at 23° C.(η_(23° C.) equal to) 98 Pa·s and mean numerical molecular weight equalto 18200 g/mole, values determined by titration with n-dodecylmercaptan.The product, following treatment at 50° C. at reduced pressure for a fewminutes, is completely odourless.

The synthesis of the silane terminated Michael polyaddition polymer iscarried out with agitation under a nitrogen atmosphere by adding 27.48 gof (A). (1.51 mmol) 0,59 g (3.02 mmol) of 3-mercaptopropyl trimethoxysilane (196.34 g/mole) and approx. 0.1% in weight of DBU. The mixture ismaintained at a temperature of 50° C. for 5 hours until the quantitativedisappearance of the acrylic double bonds determined by ¹H-NMR analysis.The NMR spectrum is consistent with the structure and does not show thepresence of secondary reactions.

The product obtained has a viscosity equal to 160 Pa·s and has only aslight odour.

The polymer placed in a metallic container under an atmosphere ofnitrogen is maintained in viscous liquid form for several days and, thatis, in a state useful for; the successive formulations.

EXAMPLE 2

In a pressure reactor, 53.7 g (26.57 mmol) of a polyoxypropylene glycoldiacrylate (<M_(n)>=2021 g/mole) are mixed with 0.81 g (23.77 mmol) ofsulphydric acid and 10.7 g of a plasticiser (adipate) in the presence ofDBU (0.1% in weight). It is left to react with agitation for approx. 8hours at a temperature of 70° C.

The product thus obtained (B) has η_(23° C.)=15 Pa·s and<M_(n)>=18400“g/mole.

Following degassing at low pressure it is completely odourless.

To 52.5 g (2.86 mmol) of the polymer (B) are added 1.12 g (5.72 mmol) of3-mercaptopropyltrimethoxy silane (196.34 g/mole) and approx. 0.1% inweight of DBU. The reaction proceeds with agitation under an inertatmosphere at T=50° C. for 5 until the quantitative disappearance of thedouble bonds.

The product obtained has η_(23° C.)=100 Pa·s and has only a slightodour.

EXAMPLE 3

In un pressure reactor, 1550.27 g (0.5729 mol) of apolyoxypropyleneglycol diacrylate (<M_(n)>=2706 g/mole) are mixed with17.35 g (0,5091 mol) of sulphydric acid in approx. 1.5 kg of toluene andin the presence of triethylamine (2% by weight). It is left to react forapprox. 10 hours at a temperature of 75° C. until the completeconversion of the mercaptan groups. The solvent is eliminated byevaporation under reduced pressure.

The product thus obtained (C) has η_(23° C.)=47.1 Pa·s and <M_(n)>=14100g/mole and is completely odourless.

To 23.22 g (1.65 mmol)” of (C) are added 0.647 g (3.30 mmol), of3-mercaptopropyltrimethoxy silane (196.34 g/mole) and approx. 2% inweight of triethylamine, with agitation under an atmosphere of nitrogen.The reaction is carried out, at a temperature of 50° C. fore 7 hoursuntil the quantitative disappearance of the double bonds.

The product obtained has η_(23° C.)=147 Pa·s and has only a slightodour.

EXAMPLE 4

A silane terminated polymer has been prepared by mixing under nitrogen29.11 g (2.07 mmol) of the product (C) of Example 3 to 0.79 g (4.13mmol) of 3-mercaptopropyldimethoxymethyl silane (180.34 g/mole) in thepresence of 0.1% in weight of DBU. The reaction is carried out at atemperature of 50° C. over 5 hours until the quantitative disappearanceof the double bonds.

The product thus obtained has η_(23° C.)=100 Pa·s and has only a slightodour.

EXAMPLE 5

In a pressure reactor, 24.36 g (12.00 mmol) of a polyoxypropylenegliycoldiacrylate (<M_(n)>=2030 g/mole) are mixed with 0.368 g (10.80 mmol) ofsulphydric acid and approx. 25 g of toluene in the presence ofdiazadicyclo octane DABCO (0.1% p). It is left to react for approx. 9hours at a temperature of 70° C. The solvent is removed by evaporationunder reduced pressure.

The product thus obtained (D) has η_(23° C.)=96 Pa·s and <M_(n)>=20300g/mole, and is completely odourless.

The synthesis of the silane terminated polymer is carried out by adding,with agitation under an atmosphere of nitrogen, to 23.56 g (1.16 mol) of(D) 0.456 g (2.32 mol) of 3-mercaptopropyltrimethoxy silane, in thepresence of 0.1% by weight of DABCO. The reaction is carried out atT=50° C. over 5 until the quantitative disappearance of the doublebonds.

The product obtained has η_(23° C.)=165 Pa·s and has only a slightodour.

EXAMPLE 6

In a pressure reactor, 62.3 g (30.49 mmol) of a polyoxypropylene glycoldiacrylate (<M_(n)>=2043 g/mole) are mixed with 0.953 g (27.96 mmol) ofsulphydric acid and approx. 60 g of toluene, in the presence of theamino catalyst DBU (0.1% by weight). It is left to react with agitationfor approx. 8 hours at T=70° C. The solvent is removed by evaporationunder reduced pressure.

The product thus obtained (E) has η_(23° C.)=102 Pa·s and <M_(n)>=24800g/mole, and completely odourless.

The synthesis of the silane terminated polymer takes place by adding,with agitation and under an atmosphere of nitrogen, to 59.3 g (2.39mmol) of (E) 0.939 g (4.78 mmol) of 3-mercaptopropyltrimethoxy silane inthe presence of 0.1% by weight of DBU. The reaction is carried out atT=50° C. for 5 hours until the quantitative disappearance of the doublebonds.

The product obtained has η_(23° C.)=185 Pa·s and has only a slightodour.

EXAMPLE 7

In a pressure reactor, 70.0 g (34.26 mmol) of a polyoxypropylene glycoldiacrylate (<M_(n)>=2043 g/mole) are mixed with 1.07 g (31.40 moles) ofsulphydric acid and 14 g of a plasticiser (phthalate), in the presenceof DBU (0.1% by weight). It is left to react with agitation for approx.8 hours at a temperature of 70° C.

The product thus obtained (F) has η_(23° C.)=37 Pa·s and <M_(n)>=24820g/mole; following degassing for a few minutes at low pressure, it iscompletely odourless. The synthesis of the silane terminated polymer iscarried out by adding, with agitation under an atmosphere of nitrogen,to 65.9 g (2.65 mmol) of the product (F) 1.04 g (5.31 mmol) of3-mercaptopropyltrimethoxy silane and 0.1% by weight of DBU. Thereaction is carried out at T=50° C. over 5 until the quantitativedisappearance of the acrylic double bonds.

The product thus obtained has η_(23° C.)=143 Pa·s and has only a slightodour.

EXAMPLE 8

In a pressure reactor, 2672.78 g (0.667 mol) of a polyoxypropyleneglycol diacrylate (<M_(n)>=4009.5 g/mole) are mixed with 18.93 g (0.555mol) of sulphydric acid and with 534 g of a plasticiser (adipate) in thepresence of DBU (0.1% by weight). It is left to react with agitation forapprox. 8 hours at a temperature of 70° C.

The product thus obtained (G) has η_(23° C.)=33 Pa·s and <M_(n)>=24100g/mole; following degassing for a few minutes at low pressure it iscompletely odourless.

The synthesis of the silane terminated polymer is carried out by adding,with agitation and under an atmosphere of nitrogen, to 2389.0 g (0.0991mol) of product (G) 38.9 g (0.198 mol) of 3-mercaptopropyltrimethoxysilane and approx. 0.1% by weight of DBU. The reaction is carried outwith agitation at T=50° C. for 6 hours until the quantitativedisappearance of the double bonds.

The product thus obtained has η_(23° C.)=149 Pa·s and has only a slightodour.

EXAMPLE 9

In a pressure reactor, 2672.35 g (1.243 mol) of a polyoxypropyleneglycol diacrylate (<M_(n)>=2149 g/mole) are mixed with 47.66 g (1.399mol) of sulphydric acid in the presence of an amine catalyst (DBU, 0.07%by weight) and approx. 2.5 Kg of toluene. It is left to react forapprox. 8-hours at a temperature of 70° C.

The solvent is removed by evaporation under reduced pressure.

The product thus obtained (H) has η_(23° C.)=65 Pa·s and <M_(n)>=16300g/mole (values determined by gel permeation chromatography andpolystyrene standards) and has a strong odour.

The synthesis of the silane terminated polymer is carried out by adding,with agitation and under an atmosphere of nitrogen, to 25.77 g (1.58mmol) of product (H) 0.83 g (3.35 mmol) ofγ-methacryloxypropyltrimethoxy silane (247.76 g/mole) and 0.1% by weightof DBU. The reaction is carried out at T=50° C. for 5 hours until themaximum conversion of the methacrylic double bonds (¹H-NMR).

The product thus obtained has η_(23° C.)=130 Pa·s and has a moderateodour.

EXAMPLE 10

In a pressure reactor, 36.88 g (0.1.154 mol) of trimethylpropanetriacrylate (319.51 g/mole) and 2110.26 g (1.045 mol) of apolyoxypropylene glycol diacrylate (<M_(n)>=2020.2 g/mole) are mixedwith 35.6 g (1.045 mol) of sulphydric acid in the presence of 3.8 g ofan amine catalyst (DBU) and approx. 3 l of toluene. It is left to reactfor approx. 8 hours at a temperature of 70° C. The solvent is removed byevaporation at reduced pressure.

-   -   The product thus obtained, branched and on average        trifunctional, (I) has <M_(n)>=19700 g/mole (values determined        by titration of the acrylic bonds) and is substantially        odourless.

The synthesis of the silane terminated polymer is carried out by adding,with agitation and under an atmosphere of nitrogen, to 1536.5 g (78.0mmol) of the product (I) 45.9 g (234 mmol) of 3-mercaptopropyltrimethoxysilane and 0.1% by weight of DBU. The reaction is carried out at T=50°C. for 6 hours until the disappearance of the acrylic double bonds(¹H-NMR).

The product thus obtained has η_(23° C.)=180 Pa·s and has a slightodour.

EXAMPLE 11

100 parts by weight of the Michael polyaddition polymer (examples: 1-10)are mixed with 100 parts of calcium carbonate, 10 parts of titaniumdioxide, 0.5 parts of an antioxidant, 1.0 part of an amine catalyst andwith a polyamidic wax in varying quantity. The mixing is carried out ina planetary machine under anhydrous conditions and in an atmosphere ofnitrogen. The product in the, form of a thixotropic fluid is degassedand placed in metallic cartridges in which it maintains its fluid form.

The product upon exposure to atmospheric humidity forms an elastic andnon sticky film in less than an hour (as a function of the amount ofcatalyst added) and cures completely in less than 24 hours.

The cured product has the following mechanical properties:

-   Hardness shore A=. 25, Elongation to rupture >200% and-   Module at 100%=0.5 MPa.

COMPARATIVE EXAMPLES Example A

In a round bottomed reaction flask, 80.19 g (38.83 mmol) of apolyoxypropylene glycol diacrylate (<M_(n)>=2060.5 g/mol) are mixed with3.747 g (34.62 mmol) of 1,3-propane dithiol (108.23 g/mol, 99% purity)in the presence of 0.1% by weight of DBU reaction catalyst. It is leftto react with agitation at a temperature of 65° C. for approx. 12 hours.

The product thus obtained (α) has η_(23° C.)=112 Pa·s and <M_(n)>=19220g/mol (values determined by titration with n-dodecylmercaptan) and has astrong, highly unpleasant, odour.

The synthesis of the silane terminated polymer takes place by adding,with agitation and under an atmosphere of nitrogen, to 73.33 g. (3.82mmol) of (α) 1.498 g (7.63 mmol) of 3-mercaptopropyltrimethoxy silaneand 0.1% by weight of DBU. The reaction proceeds at T=50° C. over 5 h,until the quantitative disappearance of the acrylic double bonds (the¹H-NMR spectrum gives confirmation).

The product obtained has η_(23° C.)=165 Pa·s and has a strong, highlyunpleasant, odour.

Example B

In a round bottomed reaction flask, 70.13 g (34.03 mmol) of apolyoxypropylene glycol diacrylate (<M_(n)>=2060.5 g/mol) are mixed with3.27 g (30.21 mmol) of 1,3-propane dithiol in the presence of 14.03 g ofa plasticiser (adipate) and DBU (0.1% by weight). It is left to reactunder agitation for approx. 10 hours at a temperature of 70° C.

The product thus obtained (β) has η_(23° C.)22 Pa·s and <M_(n)>=19150g/mol and has a strong, highly unpleasant, odour.

The synthesis of the silane terminated polymer takes place by adding,under agitation and under an atmosphere, of nitrogen, to 60.28 g (3.15mmol) of (β) 1.24 g (6.30 mmol) of 3-mercaptopropyltrimethoxy silane and0.1% in by weight of DBU. The reaction proceeds at T=50° C. for 5 hours,until the quantitative disappearance of the double bonds.

The product obtained has η_(23° C.)=98 Pa·s and has a strong, highlyunpleasant, odour.

Example C

In a round bottomed reaction flask, 75.52 g (36.65 mmol) of apolyoxypropylene glycol diacrylate (<M_(n)>=2060.5 g/mole) are mixedwith 3.529 g (32.61 mmol) of 1,3-propane dithiol and approx. 75 g oftoluene in the presence of DBU (0.1% by weight). It is left to reactunder agitation for approx. 10 hours at a temperature of 65° C. Thesolvent is removed by evaporation under reduced pressure.

The product thus obtained (γ) has η_(23° C.)=74. Pa·s and <M_(n)>=19303g/mol and has a slight odour.

The synthesis of the silane terminated polymer takes, place by adding to69.7 g (3.61 mmol) of (γ) 1.42 g (7.22 mmol) of3-mercaptopropyltrimethoxy silane and 0.1% by weight of DBU. Thereaction proceeds at T=50° C. under agitation and under an atmosphere,of nitrogen for 5 hours until the quantitative disappearance of thedouble bonds.

The product obtained has a viscosity equal to 150 Pa·s and has a slightodour.

Example D

In a round bottomed reaction flask, 30.18 g (14.04 mmol) of apolyoxypropylene glycol diacrylate (<M_(n)>=2149 g/mol) are mixed with1.176 g (12.48 mmol) of 1,2-ethane dithiol (94.2 g/mol, 98% purity) inthe presence of 0.1% by weight of DBU reaction catalyst. It is left toreact under agitation at a temperature of 65° C. for approx. 12 hours.

The product thus obtained (δ) has η_(23° C.)66 Pa·s and <M_(n)>=21122g/mol (values determined by titration with n-dodecylmercaptan) and has astrong, highly unpleasant, odour.

The synthesis of the silane terminated polymer takes place by adding,under agitation and under an atmosphere of nitrogen, to 25.43 g (1.20mmol) of (δ) 0.472 g (2.41 mol) of 3-mercaptopropyltrimethoxy silane and0.1% by weight of DBU. The reaction proceeds at T=50° C. over 0.5 h,until the quantitative disappearance of the acrylic double bonds (the¹H-NMR spectrum gives confirmation).

The product obtained has η_(23° C.=)110 Pa·s and has a very strong,highly unpleasant, odour.

Odour Evaluation

The odour evaluations have been carried out on pure silane terminatedMichael polyaddition polymers and on the products added of all theingredients necessary for the preparation of an adhesive or sealant,that is of the finished product such as that manipulated by the enduser. The evaluation of the polymer, as it is, is very important becausethe presence of unpleasant odours makes the industrial stage of theprocess problematic for producing adhesives and sealants and, therefore,its marketing to specialised companies in these types of production.

Therefore, each of the polymers synthesised has been evaluated forodours, using the following scale: 4=very strong odours, 3=strongodours, 2=moderate odours, 1=slight odours; 0=substantially odourless.

The polymer described in the U.S. Pat. No. 6,221,994 in Example 2 hasbeen used as a reference. This polymer (the “reference polymer”) has anodour value equal to 4.

The polymer synthesised in the Comparative Example C has an odour equalto 2, these synthesised in the Comparative Examples A and B have odoursequal to 3, whilst that obtained by the Comparative Example D has anodour equal to 4.

The following results have been obtained for the pure silane terminatedMichael polyaddition polymers, i.e. devoid of further loads, subject ofthe present invention: Polymers of example n°: 1 2 3 4 5 6 7 8 9 10Odour 1 1 1 1 1 1 1 1 2 1

All the silane terminated Michael polyaddition polymers have a slightodour derived from 3-mercaptopropyltrimethoxy silane, except thatreported in Example 9 which is synthesised with an excess of sulphydricacid and the odour of which derives from an incomplete elimination ofthe excess gas.

Every polymer prepared as per the Examples 1-10 has been added to bymineral loads, plasticisers and catalysts as reported in Example 11 andhas been evaluated for odours. The product described in U.S. Pat. No.6,221,994 in Example 5 has been used as a reference. This product (the“reference product”) has ah odour value equal to 2. Products of Examplen°11: 1 2 3 4 5 6 7 8 9 10 Odour 0 0 0 0 0 0 0 0 1 0

All the products are substantially odourless, except the product ofExample no 9, which has a slight odour.

1. A silane terminated polymer obtained by addition reaction between anorganic derivative of silicon and the terminal functional groups oflinear or branched polymers obtained by the Michael polyadditionreaction of sulphydric acid (H₂S) with organic compounds which have atleast two alkenyl double bonds activated by the presence, in the alphaposition with respect to each alkylenic bond, of an electronegativegroup.
 2. The silane terminated polymer according to claim 1 in whichthe organic derivative of silicon has the general formula:

with a=0, 1, 2; b=0, 1 and wherein: X=selected from the group consistingof halogen, alkoxy, acyloxy, ketoxime, amine, amide and mercaptanradicals; R¹=monovalent hydrocarbon group; R²=divalent substituentsselected from the group consisting of hydrocarbon, hetero-hydrocarbon,amino-hydrocarbon radicals; Z=substituents selected from the groupconsisting of: in which R″ represents a monovalent hydrocarbon group.


3. The silane terminated polymer according to claim 2 in which theorganic compounds of silicon of formula (1) are selected from the groupconsisting of: (Isocyanate alkyl)alkoxysilanes:O═C═N—R³—Si(R⁴)_(a)(OR⁵)_(3-a)  (1a) (Aminoalkyl)alkoxysilanes:H₂N—R³—Si(R⁴)_(a)(OR⁵)_(3-a)  (1b) (Glycidoxyalkyl)alkoxysilanes:O[CH₂—CH]—CH₂O—R³—Si(R³)_(a)(OR⁵)_(3-a)  (1)(Mercaptoalkyl)alkoxysilanes:HS—R³—Si(R⁴)_(a)(OR⁵)_(3-a)  (1d) ([metha]acrylate alkyl)alkoxysilanes:CH₂═C(R⁶)—COO—R³—Si(R⁴)_(a)(OR⁵)_(3-a),  (1e) wherein: R³=divalent alkylradical containing from 1 to 8 carbon atoms; R⁴ and R⁵=alkyl radicalsfrom 1 to 4 carbon atoms; R⁶=H or CH₃; a=0,1,2.
 4. A silane terminatedpolymer according to claim 3 in which the organic compounds of siliconare selected from the group consisting of:(3-mercaptdpropyl)trimethoxysilane;(3-mercaptopropyl)methyldimethoxysilane;(3-[metha]acryloxypropyl)trimethoxysilane;(3-acryloxypropyl)trimethoxysilane;(N-nButyl,3-aminopropyl)trimethoxysilane;(N-Ethyl,3-aminoisobutyl)methyldiethoxysilane;(3-glycidoxypropyl)trimethoxysilane.
 5. The silane terminated polymeraccording to claim 1 in which the organic compounds useful for Michaelpolyaddition, having at least two activated double bonds, are selectedfrom the group consisting of:W′[—C(R⁷)═CH₂]₂  (9)Q[-W—C(R⁷)═CH₂]₂  (9a)Q[-W—C(R⁷)═CH₂]₃  (9b)Q[-W—C(R⁷)═CH₂]₄  (9c) wherein: W′=electron-attractor group selectedfrom the group consisting of: —SO—, —SO₂—, —O—, —CO—; W—electron-attractor group selected from the group consisting of: —SO—,—SO₂, —O—, —CO—, —O—CO—; R⁷=—H or —CH₃; Q=divalent, trivalent ortetravalent group selected from the group consisting of hydrocarbonradicals, hetero-hydrocarbon radicals, polyethers, polyesters, which cancontain a repeating unit and hence have variable molecular weights. 6.The silane terminated polymer according to claim 5 in which the organiccompounds having at least two activated double bonds, are selected fromthe group consisting of: di-, tri-, tetra-acrylates; di-, tri- andtetra-methacrylates; di-, tri- and tetra-vinylsulphones.
 7. The silaneterminated polymer according to claim 6 in which the organic compoundsuseful for Michael polyaddition, having at least two activated doublebonds, are composed of organic acrylics and/or methacrylics of generalformula:

wherein m=2, 3, 4; R⁷═H or CH₃; R⁸ is selected from the group consistingof: di, tri or tetravalent polyethers which consist essentially ofchemically combined —OR⁹— units, wherein R⁹ is a divalent alkyl grouphaving from 2 to 4 carbon atoms; di, tri- or tetra-valent linear orbranched aliphatic alkyl radicals, preferably from 1 to 50 carbon atoms;di-, tri- or tetra-valent aromatic radicals, preferably from 6 to 200carbon atoms; di-, tri- or tetravalent linear or branched aryl radicals,preferably from 6 to 200 carbon atoms; or R⁸ is one or more combinationsof said polyethers, alkyl radicals, aromatic radicals, aryl radicals. 8.The silane terminated polymer according to claim 7 in which thedi-acrylate and di-methacrylate organic compounds are selected from thegroup consisting of: compounds of formula (11)

wherein R⁷═H or CH₃; R¹⁰=selected from the group consisting of—CH₂—CH(CH₃)—, —CH₂—CH₂—, —CH₂—CH₂—CH₂—CH₂—; —CH₂—CH(CH₃)—CH₂—;n′=integer comprised of between 1 and 400, preferably between 0.1 and200, still more preferably between 1 and 50; compounds of formula (12):

wherein n is an integer comprised of between 0 and 10 and R⁷ is H orCH₃.
 9. The silane terminated polymer according to claim 8 in which thedi-acrylate organic compounds are the polyisopropylene glycoldiacrylates.
 10. The silane terminated polymer according to claim 7 inwhich the tri-acrylate and tri-methacrylate organic compounds are:

wherein: R⁷═H or CH₃; n″=an integer comprised of between 0 and 400,preferably between 0 and 200, still more preferably between 0 and 50.11. The silane terminated polymer according to claim 6 in which thevinyl-sulphonic organic compounds are:

wherein R¹¹ is selected from the group consisting of —CH₂—CH(CH₃)—,—CH₂—CH—, —CH₂—CH₂—CH₂—CH₂—CH₂—CH(CH₃)CH₂; n′″=an integer comprised ofbetween 0 and 400, preferably between 0 and 200, still more preferablybetween 0 and
 50. 12. A synthetic process for a silane terminatedpolymer obtained by the addition reaction between an organic siliconderivative and the terminal functional groups of linear or branchedpolymers obtained by the Michael polyaddition reaction of sulphydricacid (H₂S) with organic compounds which have at least two alkylenicdouble bonds activated by the presence, in the alpha position withrespect to each alkylenic bond, of an electronegative group, the processin which the Michael addition reactions are catalysed is by organicbases.
 13. The process according to claim 12 in which the organic basesare tertiary amines.
 14. The process according to claim 13 in which thetertiary amines are selected from the group consisting of:triethylamine, 1,8-diazadicyclo[5.4.0.]undecene-7 (DBU),1,4-diazadicyclo[2.2.2]octane (DABCO).
 15. The process according toclaim 14 in which the tertiary amine is 1,8diazadicyclo[5.4.0.]undecene-7 (DBU).